Pivoted-leg compass



Oct. I4, 1947. E. E. FIFE PIVOTED-LEG CQIGPASSV Filed July 2,6, 1944Patented Oct. 14, r1947 OFFICE fPIvoT-ED-LEG CoMrAss .Elmer in.FifaDetfoit, Mich.

lAppiaation only '26, 1944, 'Serial No. v5413,614

(c1. ss-m) SClaima The invention "relates to a two-'legged fscrilc'in-gor similar instrument ior use in orming -circles and arcs whether ininkl or"pencfl,-or'finthe lform .of .a merezscratch.

-|The r principal object-.of the linvenition iis ito `provide a novel:and eflectiveinstrument for--ac'cu- .l'ately scribing circles 'onsteel, vparticularlysmall circles, say for .1/3 to vextremely smallones.

A further object is torprovideiafnovel constructhe -work .even if theinstrumentisfnotfheld `truly ,perpendicularto the work.

vAnother y object of the .invention is .'-toprovide .1 a novel andiadvantageous .construction `wvl'iereloythe v-pivot legof the instrument'will-.loe Iheld against the work withfainuch-.greatery pressurecomponent than the s'cribing leg, tofhold'saidpivot.leg-againstA.slipping from the:proper centerl'pointabout--wl'iich -anV arc orcircle' is .to be described.

Yet another object is to provide .fa "new .and iimproved Vconstructionfor .bracing the :"scrioing leg against twisting and tfending 'tolagbehind lduring operationof the instrument.

A fur-ther object is fto provide fagnovel "andsadvantageousquick-.acting.adjustingrmeans forati- .J' listingY thescribinglegtowardaand :fror'nt-hepivot zleg.

.-A still v.further:object is tolprovidesa xzomparav.tivelysimpl-eandinexpensive Tinstrument, :gettone which willloe-easily.operable,-reliablezanddurahle.

With :the .foregoingin view, the invention fre- `.sides .in the .novelsubject :mat-ter :hereinafter fdescribed and claimed, :descriptionnein-g Saccomplished by reference to the accompamngfdraw'- Ling. y

Figure 1. is a -side .elevation of -t'he :instrument .the scribing legbeing .ini-the slightly raised @osition which itoccupiesyheiterefdownwa11d Lpressure Sisplaced upon the' operatingfknob.

Fig. 2 is -a vertical sectional viewgtnescriioing leg being lowered tooperative position bynnwn- Ward pressure upon the knob.

Figs, 3, 4 and 5 are-:sectionalviewszasindicarted by the correspondinglyvnumberedlines fof vl.

l.A preferred construction :has lbeenlillustrat'ed .and will beratherfspecically;describedwithithe understanding, however, .that Withinthe scopehdf the inventionv as'.clairned,avariations;may 'loeimada A.Thepivot yleg of .theinstrument ,.islin r-th'e .'f'orrn ofa vertical vshaft6 .having :aipoint il at its '.lower i" fend, said point Abeing 'by'preference adjustably :held inran appropriate -ichuck @8. Slidable uponthe upper end of the '.shaft, .i'sran operating knob 9 which isrnormally.heldin faraised Vposition :by

:means .of a compression l:spring .10 .housedtwithin the bore Il, whichbore also receives the upper Yend of .said/,shaft '-6. A slight distancebelow the vknob 9, the shaft l is formed with a diametrical Islot 'l2fora purpose to appear, and said knob'is provided with adownwardly'projecting .bifurcated lug rI3 at one end of said slot, foraV purpose which will also later appear.

A sleeve I4 is slidalole vertically'on the shaft and is by preferenceprovided withbushings. I5. At itsupper end,the sleeve l 4 is formedvwith two -laterallyvprojecting,parallel lugs |16 between which the.upper-end of the scribing leg Il is pivoted by means of ascrew or thelike I8. The lower end of this leg is provided `with a `suitable clamp.I3 for holding a scribing `point la, a pen or a piece oflead. Twoparallelarms 20 are formed ori-the inner edge of the leg ll, said armsstraddling the sleeve I4 to b-race said leg and prevent it fromtwistingfandvlagging during operation of the instrument. YIn the presentdisclosure, the sleeve I5 is formed with a ho-llow lug 2! projecting toyward the leg Il, said lug being of rectangular form and having itsvertical sides disposed against the .arms 2E) of said leg I'l. .Thesleeve I4, with its lugs .mand 2| may well bero-rmed from a single.metal blank lwhich mayhave its meeting edges welded or otherwise joinedafter being bent to forml said sleeve. It is also preferable to form theleg |"l and its arms 2B from a single metal blank which is of such formas to give said leg a channel shape 'in crosssection with its channeldisposed toward the leg or shaft 6, said arrnsZ being integral with theside flanges 22 of said leg l?.

The inner side of the leg il is formed with.a curved seat '23, and 'saidleg is also formed with an opening 24 from this seat to the side of'said leg remote from the sleeve lil. A block 25, `constitutinga nut,isirockably"engaged'with the seat 23, being preferably of cylindricalform. Ascrew 2S, shown as having a left-hand thread, is threaded throughthe nut 25, the outer end of said'screw having an operating knob 2l.This screw is of 'tubular form 'and its interior is providedwith'aright-hand screw Ythread engaging a right-'hand screw 28. vThisscrew'extends into the hollow boss ft and is pivoted'thereto by a.suitable pin or rivet 21.21.

An Lelongated yoke formed "from spring wire, straddles the screw 26A"between the'fsidenasnges'z ofthe scribing leg Il Afandbearsagainstithe 'blockfor'nut 25 to hold the latterrockablyrengagedwith the seat 23, the vends fof sai-:lyoko 'i3dbeingsecure'd Ato said leg I1 "by '-suitablelmeansi such asbolts andwashers.

*Byturning-'the knob 27,113 one directionfor 'the 30 which ispreferablyv other, it will be seen that the scribing leg I1 will bequickly adjusted inwardly or outwardly as desired, the speed ofadjustment being much greater i than if only a single screw wereprovided.

A short lever 32 projects laterally from the leg or shaft 6 .and isdisposed between the lugs I6 of the sleeve 4, said lever having arounded inner end 33 received in the slot I2 of said leg or shaft 6. Aslot 34 is formed in the outer end of the lever 32 and the Screw or thelike I8 extends through this slot, to pivotally connect the lever 32with the sleeve I4. Between its ends, the lever 32 is straddled by thebifurcated lug I3, to which it is pivoted by a pin 35. This pin isrelatively close to the inner end 33 of the lever 32 and is relativelydistant from the outer end of said lever. This lever, by having its end33 in the slot I2, is fulcrumed upon the shaft or leg 6, and the partsare so proportioned that the upward thrust on the knob 9, caused by thespring I0, causes the lug I3 to swing said lever upwardly as shown indotted lines in Fig. l. The outer end of this lever, being connectedwith the sleeve I4 by means of a screw or the like I8, vthus normallyholds said sleeve and the scribing leg Il in a raised position as seenin Fig. 1. When the instrument is to be used, however, and a downwardforce is exerted on the knob I9, as indicated by the arrow in Fig. 2,said knob slides downwardly upon the leg or shaft 6, causing the pin 35to swing the lever 32 downwardly as seen in full lines in said Fig. 2.This downward swing of lever 32 slides the sleeve I4 downwardly upon theleg or shaft 6, and the scribing leg I'I of course moves downwardly withsaid sleeve until its scribing point or the like 'Ia contacts with thesurface to be marked. Then, while the instrument is being rotated tomark the work, the downward pressure on the knob 9 s of coursecontinued. This downward force will be split into two components, oneacting downwardly on the pivot leg 6 and the other acting downwardly onthe scribing leg Il, and due to the location or the pivot 35 near theinner end 33 of the lever 32, the component acting on said pivot leg 6will be much greater than `for carrying out the objects of theinvention. At-

tention is again invited to the possibility of making variations Iwithinthe scope of the invention as claimed.

I claim:

l. A scribing or similar instrument comprising two legs, an operatingknob slidably mounted on one of said legs, and connecting means betweensaid knob and legs including a one-piece lever movable relative t saidlegs by downward pressure on said knob, said lever being connected atone end to one of said legs, connected at its other end with the otherof said legs and connected near said one end with said knob, wherebydownward pressure on said knob will result in a relatively strongdownward component on said one of said legs and a relatively weakdownward component on the other of said legs, said one Qisaid legshaving a point at its 1ower end constituting a pivot for the instrument,said other of said legs having a scribing point.

2. A scribing or similar instrument comprising a vertical shaft having apoint at its lower end constituting a pivot for the instrument, a knobslidable vertically on the upper end of said shaft, a sleeve slidablevertically on said shaft under said knob, a leg at one side of saidsleeve and having a scribing point at its lower end, means forconnecting said leg with said sleeve, a vertically swingable leverextending laterally from said shaft and fulcrumed at its inner end onsaid shaft, the outer end of said lever being connected with said sleeveto downwardly slide the latter on said shaft when said lever is swungdownwardly, and means between the ends of said lever and connecting saidlever with said knob for downwardly swinging said lever when said knobis downwardly slid, said means being relatively close to said inner endof said lever and relatively distant from said outer end of said leverto cause said lever to exert a greater downward component on said shaftthan on said leg.

3. A scribing or similar instrument comprising a, leg having a point atits lower end constituting a pivot for the instrument, a second leghaving a scribing point at its lower end, a slidable member on one ofsaid legs, a knob adjacent the upper ends of said legs and slidablymounted on the first mentioned leg, and connecting means between saidknob, said slidable member and the upper ends of both of said legs, saidconnecting means includingY a one-piece lever pivoted between its endsto said knob and extending transversely with respect to said slidablemember and said legs, said lever being movable relative to said legs bydownward pressure on said knob.

4. A scribing or similar instrument comprising a vertical shaft having apoint at its lower end constituting a pivot for the instrument, a knobslidable vertically on the upper end of said shaft, a sleeve.. slidablevertically on said shaft under said knob, a leg at one side of saidsleeve and having a scribing point at its lower end, means forconnecting said leg with said sleeve, a vertically swingable leverextending laterally from said shaft. and fulcrumed at its inner end onsaid shaft, the outer end of said lever being connected with said sleeveto downwardly slide the latter on said shaft when said lever is swungdownwardly, and means between the ends of said lever and connecting saidlever with said knob for downwardly swinging said lever when said knobis downwardly slid.

5. A structure as specified in claim 2; said means for connecting saidleg with said sleeve including a pivot for said leg and a lateral lug onsaid sleeve through which said leg pivot extends, said leg pivot and lugconstituting the means for connecting the outer end of said lever withsaid sleeve.

6. A scribing or similar instrument comprising two legs, a slidablemember on one of said legs, a pivoted connection between the other ofsaid legs and said slidable member, a one-piece lever extendingtransversely to the longitudinal axes of said legs and having one endfulcrumed to said one of said legs and its other end pivotally connectedto said slidable member, and a knob slidably mounted on one of said legsand pivotally connected to the intermediate portion of said lever at apoint closer to said one of said legs, whereby downward pressure on saidknob will result ina relatively strong downward component on said .oneof said legs and a relatively weak downward component on the other ofsaid legs, said one of said legs having a point at its lower endconstituting a pivot for the instrument, said other of said legs havinga scribing point.

7. In a scribing or similar instrument, a leg h'aving a curved seat inits inner side and an opening from said seat to its outer side,leg-adjusting means including a nut having a curved surface rockablyengaging said curved seat and a screw threaded through said nut andextending through said opening, an elongated yoke straddling said screwand extending longitudinally at the inner side of said leg, said yokebearing between its ends against said nut to hold the latter engagedwith said seat, and means securing the ends of said yoke to said leg,said leg being of channel shaped cross section, said nut and yoke beingdisposed in the channel of said leg.

8. A scribing or similar instrument comprising a leg having a point atits lower end constituting a pivot for the instrument, a. knob having adownwardly opening socket to slidably receive the upper end of said leg,a coil spring in said socket above the top of said leg, a sleeveslidable on said leg beneath said knob, a transverse lever fulcrumed ato ne of itsends to said leg and havl 6 ing its other endpivotallyconnected to said sleeve, the intermediate portion of saidlever being pivotally connected to said knob, a second leg having ascribing point at its lower end and its upper end pivotally connected tosaid sleeve, and a screw-threaded adjusting means between said sleeveand the intermediate portion of Said second mentioned leg.

ELMER E. FIFE.

REFERENCES CITED The following references are of record in the le -ofthis patent:

UNITED STATES PATENTS n

